ATLANTA — The worldwide shortage of a drug used in executions reverberated this week in two of the most active death-penalty states as Texas announced it would replace the anesthetic in its three-drug regimen and federal agents seized Georgia’s supply.

The seizure on Tuesday of the powerful barbiturate — sodium thiopental — at the Georgia Diagnostic and Classification Prison in Jackson, site of the state’s death row, has at least temporarily blocked future executions, although none are now scheduled.

In Texas, where the administrative change was announced Wednesday, lawyers for an inmate scheduled to die next month are preparing to challenge the substitution of the new drug.

The moves in both states continue the fallout from the January announcement that Hospira Inc., the only American producer of sodium thiopental, had stopped making the anesthetic. The shortages began after the company suspended production in 2009 because of problems obtaining an ingredient. They now have become dire because the drug’s shelf life is typically no more than two years.

Many of the 34 states with the death penalty (Illinois repealed its law last week) have been scrambling for months to find stores of sodium thiopental or to replace it with other drugs with similar effects. Several states have delayed executions because of its unavailability. Texas has 314 inmates on death row; Georgia has 99.

In most state lethal injection protocols, sodium thiopental is first used to anesthetize the inmate, and then other drugs are administered to paralyze the body and stop the heart.

Tuesday’s seizure by the Drug Enforcement Administration presumably responded to a February complaint lodged by a lawyer for Andrew Grant DeYoung, who faces execution for killing his parents and sister in 1993.

The lawyer, John T. Bentivoglio of Washington, wrote Attorney General Eric H. Holder Jr. on Feb. 24 that Georgia’s Department of Corrections appeared to be importing sodium thiopental from a British distributor. Because the state does not have a federal license to import controlled substances, that would violate the Controlled Substances Act, Mr. Bentivoglio charged.

Drug Enforcement Administration officials declined to comment Wednesday about the precise nature of their investigation. The Georgia Department of Corrections said it was cooperating and would otherwise reserve comment.

Mr. Bentivoglio said lawyers learned through e-mails produced by an open-records request regarding another Georgia death penalty case that the state bought 50 vials of sodium thiopental in July from Dream Pharma Ltd., a London wholesaler.

He said the seizure demonstrated that the federal drug agency had taken his assertions seriously. “It’s clear that the potential unlawful import of this drug was more than a mere paperwork violation,” he said.

In Texas, the Department of Criminal Justice announced that it would replace sodium thiopental in its three-drug process with pentobarbital, another sedative. The state’s supply of sodium thiopental expires this month.

The Texas change follows a procedure adopted by Oklahoma, which first substituted pentobarbital in its executions in December. Last Thursday, Ohio executed an inmate using only pentobarbital in a large dose.

The Danish company that makes pentobarbital, Lundbeck Inc., has informed states that it is “adamantly opposed” to the use of its product in executions. But a number of states continue to explore its use as a substitute.

“Obviously, there is a precedent for its use in executions,” said Michelle Lyons, a spokeswoman for the Texas agency, who said Texas law allowed corrections officials to change the drugs without legislative approval.

Maurie Levin, a lawyer who represents Cleve Foster, a murderer scheduled to die in Texas on April 5, said she would challenge the timing and process for making the change.

“We believe that under state law they are required to have some sort of vetting process,” Ms. Levin said.

ATLANTAA U.S. shortage of a key lethal injection drug deepened Wednesday as federal regulators investigated whether Georgia circumvented the law in obtaining its supply and Texas announced it was switching to an alternative.

The Drug Enforcement Administration seized Georgia's entire supply of sodium thiopental, which defense attorneys claim came from a fly-by-night British supplier operating from the back of a driving school in a gritty London neighborhood.

DEA agents have not said exactly why they seized the drug, except that there were questions about how it was imported into the U.S.

The supply issues have delayed executions in several states and forced at least five to turn to England for the drug, a sedative in the three-drug execution cocktail used by most of the country's 35 death penalty states. Texas on Wednesday announced it is switching to another, stronger sedative that is often used to euthanize animals.

The seizure in Georgia effectively delays any executions until the federal probe is complete, which could take months. That's little comfort to friends of Emmanuel Hammond, a 45-year-old who was executed in January even after his attorneys argued that the state could have illegally obtained the drug.

«There's something terribly wrong when officials charged with enforcing criminal laws break them,» said Brian Mendelsohn, an attorney for Hammond, who was put to death for the 1988 slaying of an Atlanta preschool teacher.

Georgia corrections spokeswoman Joan Heath said the state is cooperating with the DEA probe to ensure it is in «regulatory compliance with the DEA over how we handle controlled substances.

Georgia's stockpile of sodium thiopental _ believed to be around 20 grams, enough for at least four executions _ has been under scrutiny since corrections officials released documents in court that showed the state bought the drug from Dream Pharma, a company in London that has the same address as the Elgone Driving Academy.

The firm hasn't responded to several e-mail and phone calls seeking comment, and a reporter who visited the store Wednesday was told the owner was gone for the day.

The documents also show the drugs were manufactured by Link Pharmaceuticals, a firm purchased five years ago by Archimedes Pharma Limited. Both are British firms. Death penalty opponents say the name of Link Pharmaceuticals hasn't been on labels since May 2007, and since sodium thiopental typically has a shelf life of four years, the state's supply would expire in May of this year.

State corrections officials say the drug won't expire until 2014 and they don't have concerns about its quality.

Sodium thiopental has been in short supply since Hospira Inc., its sole U.S. manufacturer, decided in January to stop making it. An Associated Press review this year found that most of the nation's 35 death penalty states had run out of it or would soon; 17 states had no supply at all.

The Texas Department of Criminal Justice said Wednesday it was planning to substitute pentobarbital for sodium thiopental in its three-drug cocktail. Agency spokeswoman Michelle Lyons said the state picked the drug partly because it survived court challenges in Oklahoma, where it has been used in recent executions. Ohio has also switched to pentobarbital as the sole drug used for its executions.

In some other states, switching to another drug could prove a difficult, drawn-out process, fraught with legal challenges from death row that could put executions on hold.

The shortage has delayed executions in several states and the Associated Press review found that at least five states _ Arizona, Arkansas, California, Georgia and Tennessee _ had to turn to England for their supply of the drug.